1. Field of the Invention
The field of the invention is computer memory subsystems for enhancing signal quality.
2. Description of Related Art
The development of the EDVAC computer system of 1948 is often cited as the beginning of the computer era. Since that time, computer systems have evolved into extremely complicated devices. Today's computers are much more sophisticated than early systems such as the EDVAC. Computer systems typically include a combination of hardware and software components, application programs, operating systems, processors, buses, memory, input/output devices, and so on. Advances in semiconductor processing and computer architecture have served to push the performance of the computer higher and higher and have resulted in computer systems today that are much more powerful than just a few years ago.
Throughout the advancement of semiconductor processing and computer architecture, advancements in computer memory subsystems have played an important role in creating more powerful computers. To maintain the steady overall increase in computer performance, increases in the speed of computer memory subsystems have complimented increases in speed of computer processors. Over the last several years, increases in the performance of computer memory subsystems have increased by several orders of magnitude. Just a few years ago, the operational speed of computer memory subsystems was measured in kilohertz. Today, the operational speed of computer memory subsystems is measured in megahertz.
Currently, the Joint Electron Device Engineering Council (‘JEDEC’) serves as an important source of computer memory subsystem performance standards in the electronics industry. JEDEC was founded in 1960 and is the semiconductor engineering standardization body of the Electronic Industries Alliance (‘EIA’). EIA is a trade association that represents all areas of the electronics industry and works to promulgate standards throughout the electronics industry that meet the needs of both manufacturers and consumers.
In the area of computer memory subsystem performance standards, the JEDEC standards support computer memory subsystems that include various numbers of Dual In-Line Memory Modules (‘DIMM’). As the number of DIMMs in a computer memory subsystem increases, however, the speed at which the computer memory subsystem operates is reduced because increases in memory bus load increase signal distortions along the bus. These signal distortions are typically caused by signal reflections or inter symbol interference occurring in the memory bus.